The excessive consumption of potable water remains a dilemma for water agencies, commercial building owners, homeowners, residents and sanitaryware manufacturers. An increasing global population has negatively affected the amount and quality of suitable water. In response to this global dilemma, many local and federal authorities have enacted regulations that reduce the water demand required by toilet flushing operations. In the United States, for instance, government agencies that regulate water usage have gradually reduced the threshold for fresh water use in toilets, from 7 gallons/flush (GPF)(26.5 liters/flush (LPF)) prior to the 1950s to 5.5 GPF (20.8 LPF) by the end of the 1960s to 3.5 GPF (13.3 LPF) in the 1980s. The National Energy Policy Act of 1992 now mandates that toilets sold in the United States can only use 1.6 GPF (6 LPF) (see “Toilets”, www.urbanedge.org/green-housing). Other countries through North and South America, Europe, Asia and Australia have enacted similar restrictions in recognition of global water conservation objectives.
In the sanitary industry, however, a toilet must successfully perform two operations within prescribed legislative limits for water usage. The toilet must not only achieve unimpeded removal of all waste from a toilet bowl, but also effect complete removal of surface markings from the bowl interior. Even with water usage restrictions, consumers expect successful completion of both functions without the need for successive, redundant flushes and/or redundant brushing and scrubbing.
Prior to inception of water restriction regulations, contemporary toilets employed principals of gravity to complete these functions. Such toilets operated essentially by pouring a large amount of water into the bowl and relying upon the inherent low-pressure flow for sufficient operation thereof. The significant reduction of available flush water, however, prompted radical design changes to then-existing toilets designs and impeded the ability to achieve an effective flush. For example, reduction of flush water volume from 3.5 gallons (10 liters) to 1.6 gallons (6.0 liters) in the United States revealed the poor hydraulic design inherent in existing toilets and forced sanitaryware manufacturers to reduce the diameter of the toilet exhaust pipe by up to 1.5″ (3.8 cm). This design modification produced a funnel whereby the toilet aided the siphon function. The reduced exhaust pipe parameter, however, exacerbated clogging and required multiple flushes for complete elimination of waste and surface markings from the bowl interior, thus eliminating any water reduction benefits.
Although the above problems are not applicable to gravity-fed toilets, water restriction regulations also incurred problems in Europe, where such gravity-fed, non-siphoning toilets are configured for installation in floor or wall outlets (thereby ensuring compliance with regional codes). Unlike American designs, such non-siphoning configurations typically have deep bowls, small water spots and enhanced exhaust pipe diameters from about 2.5″ (6.4 cm) to about 3″ (7.6 cm), inclusive, that are not prone to clogging. The small water spot, however, increases the dry surface area of the ceramic bowl that is exposed to soil. This increased surface area inhibits bowl cleanliness and exacerbates the need for consistent manual bowl cleansing.
Sanitaryware manufacturers, learning from their initial mistakes, thereafter made significant progress in toilet design and operation to perform the waste removal and cleaning functions described hereinabove. Most manufacturers employed new features in these designs, namely, a very powerful jet that helped to arrange the siphon at a larger exhaust diameter (in siphoning toilet models typically found in the united States and Asia); and a constant diameter exhaust pipe with almost no restrictions (in siphoning and non-siphoning models). In the United States, for instance, multiple toilet models emerged that incorporated improved hydraulic design, often fed by 3″ (7.6 cm) discharge valves in the toilet tank to create a powerful jet. Such toilets remove a demonstrably larger load within the 1.6 GPF (6 LPF) water limit when compared to their predecessors (see, for example, U.S. Pat. No. 5,123,124 for “Automatic, Self-Cleaning, Water-Saving Toilet System”; U.S. Pat. No. 6,115,853 for “Toilet Bowl”; U.S. Pat. No. 6,332,229 for “Automated Flap and Cup Cleaner Water-Saving Toilet”; and U.S. Pat. No. 6,470,505 for “Water Efficient Toilet”).
A common drawback of conventional gravity-force dynamic toilets is the removal of the majority of water by a strong jet during the flush function. The powerful jets employed thereby use a significant portion of available water for the flush, leaving a minimal amount of water for a rim wash and correspondingly little capability for sufficient cleaning of the bowl interior. Such toilets additionally have problems with consistent excess noise during use and often incur uncomfortable splashing of toilet water. It is therefore desirable to explore other energy sources that exhibit enhanced toilet performance and water conservation benefits.
Line pressure as an energy source provides simple, reliable performance without the need for electricity and without the need for a tank (if direct flow from a 1″ (2.5 cm) line is used). Conversely, line pressure is not immediately available in many markets (and in Europe, legislation exists to prevent the use of line pressure). In addition, line pressure as an energy source requires use of a heavy and expensive water control valve with dependence on inherent line pressure and undesirable noise and water flow characteristics. This type of energy source is not compatible with residential applications where the line is ½″ (1.3 cm).
In the alternative, pressure accumulators are used for toilets to provide sufficient flushing performance without the need for electricity. These toilets require an additional tank and exhibit dependence upon preexisting line pressure. Because the water pressure changes significantly during discharge (producing high water pressure at the initiation of water discharge yet low water pressure at the end of such discharge), the average pressure during the flush cycle is approximately half of the line pressure or the pressure regulator pressure. The need for a pressurized vessel results in excessive noise and water flow control, presenting the consumer with a sub-optimal solution (see “Toilets: Comfortable and Efficient”, Consumer Reports, August 2005).
Both pressure line and pressure accumulator systems simultaneously direct water to a toilet rim and jet simultaneously (using either option still requires optimum distribution of water flow between the jet and the rim, although hydraulic water control devices devised for this purpose remain complicated, expensive, inflexible and incapable of proper water flow distribution.). The pressurized jet pushes out the sump load quickly, and this event is comparatively silent because the energy of the jet is damped by water in the sump. When the sump becomes empty, pressurized water shoots out of the jet into the air, thereby creating a high decibel noise (the noise level in pressure assisted toilets is about 85 dB, slightly louder than the 80 dB noise level of a conventional vacuum cleaner, as compared with a noise level at or about 78 dB for conventional gravity toilets). To prevent such noise, the jet flow must be stopped when the sump is empty. Excessive noise is an important factor in toilet selection, as installation of noisy toilets is limited to public places and not appropriate for private residences or places of relaxation (i.e., hotels, spas, hospitals, residential care facilities, etc.).
In addition, pressurized jets in these systems create splashing of water that has not yet evacuated the bowl. As a consequence, splashing on the rim creates an unhygienic condition and also fails to adequately remove surface markings of waste from the bowl interior.
Flexible electrical controls and electric pumps are an alternative to line pressure for energizing toilets. Despite the fact that toilets with electric pumps have been known for some time (see, for instance, U.S. Pat. Nos. 3,986,216; 3,932,901; 4,185,337 and 5,010,602, the disclosures of which are incorporated by reference herein), few toilets currently on the market have an electric pump. Examples of this type of toilet include one-piece embodiments with a very low tank within which the pump resides and induces flow (see, for example, the product specification for Kohler's “Trocadero” toilet) and a tankless toilet that hides water storage in a shroud beneath the tank (see, for example, the advertisement and product specification for Kohler's “Purist Hatbox” toilet). In the latter example, a pump pushes water into the jet and rim, and electric and water supply lines disposed beneath the toilet support surface enter the toilet from a bottom portion thereof. Such compact construction is aesthetically pleasing and accommodates flushing under a strong pressurized jet action. This example, however, lacks proper timing and distribution control of water between the rim and the jet. The result is a weak bowl wash due to the lack of sufficient water delivery at the rim. In addition, splashes caused by the jet escape the bowl interior, causing likely discomfort to the user. The jet continues to run when the sump is already empty, and excessive noise is prevalent during the flushing action.
Conventional toilet designs still use a significant amount of water to complete a flush cycle, especially in consideration of contemporary water conservation efforts. Applicant of the instant application has addressed the need for powerful, cleansing flushes in 1.6 GPF/6.0 LPF embodiments (see Applicant's U.S. Pat. No. 6,728,975 and Applicant's pending U.S. application Ser. No. 10/231,977, the disclosures of which are incorporated by reference herein). Applicant's disclosures provide a toilet with an exhaust pipe having a diameter of about 2 and ⅜″, thereby obviating most clogging conditions. In the commercial embodiment of Applicant's disclosed toilet, 1.2 gallons (4.5 liters) of water is discharged from the tank in about 0.7 seconds, and a complete flush takes about 3 seconds. This device may be integrated with electronic timers integrated into a control circuit, such timers being more adjustable and cost effective than analog mechanical flow control devices.
Applicants have observed, however, that it is desirable to provide a toilet having an improved flushing system and operating method therefor, such flushing system using an alternative energy means with minimal water consumption and without any detriment to flushing performance. Such a flushing system operating method is desirably employed in a plurality of siphoning and non-siphoning toilet configurations for global applications (desirably using a water volume at about or below 1.6 gallons (6 liters)). Such an operating method should ensure load removal from the sump with minimal flushing noise but with comprehensive bowl cleaning without the need for plungers and/or brushes. The employed flushing system can be readily installed in cooperation with any preexisting water supply line (including ½″ (1.3 cm) diameter residential water supply lines). The desired flushing system configuration will permit compact toilet designs to facilitate installation and maintenance thereof and affordability for a wide range of commercial and residential consumers. By using minimal water amounts to achieve an effective flush and thereby maintain optimal bowl cleanliness, such an operating method desirably reduces consumption of potable water without compromising sanitation.